I have the Exotek kit and I think it is well worth the money , my MLST2 turns like its on rails and the servo has held up too LOTS of really heavy bashing
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I have heard you can also dremel the chassis and fit Hitec HS65 mg servos , but after its all said and done you will be paying almost as much for the dual servos as you would for the Exotek chassis . You can use any 1/10 servo with it , even plastic geared ones would hold up .